Why did human evolution move towards the pursuit of intelligence rather than physical strength?

Many people believe that mental labor is more advanced than physical labor. Not to mention modern people, even some of the great works of the past, such as Aristotle's "Politics", Lao Tzu's "Tao Te Ching" and Veblen's "The Theory of the Leisure Class", have made similar statements. What's going on? Why do people generally have such a perception?

In fact, the fact that physical labor is inferior to mental labor essentially reflects the need and choice of intelligence in the process of human evolution. Let's talk about it today!

01. Why did human evolution move towards the pursuit of intelligence rather than physical strength?

I don’t know anything about sociology, but we might as well go a step further and ask this question: “Why did human evolution move toward the pursuit of intelligence rather than physical strength?”

If a phenomenon belongs to a certain era, such as the Enlightenment or the red in the 1960s, then there are more sociological factors. If a phenomenon lasts for thousands or even millions of years, then I think there may be deeper reasons for this phenomenon , just like what I mentioned in a reply to "From a biological point of view, why are girls shorter than boys on average? - Answers from Zhihu users", this continuous phenomenon is actually more of a biological choice. And brain capacity just fits this choice. Between 6 million and 3 million years, brain capacity has basically not changed. However, 2 million years ago, this number began to increase continuously, which means that the active choice began to continue to strengthen, that is, humans' pursuit of intelligence has a history of at least 2 million years.

In contrast, aspects of our physique, including body shape, do not seem to have changed as dramatically (humans vs apes/gorillas).

We use a gene ARHGAP11B to introduce this screening process:

Humans and chimpanzees share about 99% of their genes, but the human brain is three times larger than that of chimpanzees. In this process, there is an obvious gene ARHGAP11B, which helps the basal brain stem cells to multiply, resulting in more neurons being produced during the development of the human brain, increasing the volume of the brain responsible for advanced cognitive abilities such as speaking and thinking.

To verify the role of this human-specific gene in brain development, researchers implanted the gene into mouse embryos. The results showed that under the influence of this gene, the number of mouse brain stem cells increased significantly. About half of the experimental mice even had neocortical folding that only occurs when the human brain develops. Scientists believe that this experimental result means that this gene played a key role in the evolution of the human brain.

Even more fascinating is that only humans and our now extinct relatives, the Neanderthals and the Denisovans, have this gene.

Anyone who understands evolution knows that mutations occur randomly, while selection is directional. When ARHGAP11B appeared, I believe that this group will have polymorphisms at the same time, some have this copy, and some do not. In the end, those who have this gene will gain an advantage and eventually evolve into humans, while those who do not have it or have fewer copies will be eliminated.

Since this gene is not related to dietary diseases like other genes, but is closely related to brain capacity, it can be seen that, at least in this era, the selection of intelligence already exists. It can be seen that our selection of intelligence is consistent and is also the essential reason reflected in various theories and social phenomena.

02. Why do humans have IQ?

When geographical division caused the forests in the east of the Great Rift Valley of East Africa to gradually disappear, the ancestors of humans, the apes, were forced to come down from the trees. At this time, the apes that lived on fruits and leaves were forced to change their living strategies. The changes are as follows:

1. Walking upright. Because the grass is dense, many beasts hide in the grass and come down from the trees. The lack of apes looking down from high places forces them to walk upright, which can improve the apes' alertness and vision.

2. Free your hands. Since you don’t need to climb, your upper limbs are free.

3. Hunting became more difficult. Due to the lack of food on the grassland, omnivorous primates began to try to catch more animals, which required the emergence of intelligence.

Although apes are larger animals, humans do not have a great advantage among predators.

The speed is not fast enough.

2. Lack of skin protection,

Insufficient meshing capacity of three teeth

Lack of muscle explosiveness

The above determined that humans did not have much advantage in hunting, so a new model had to be adopted. Humans adopted a teamwork approach, and this collaboration required intelligence. Of course, you think humans can take actions similar to hyenas, but if that were the case, humans would not be able to go to the whole world and would only be confined to one corner, like many apes, but to hunt more, overcome many difficulties, and even make tools, design traps, and provide more strategies. These complex collaborations require very high intelligence. This is why, at this time, the brain capacity of the hominids began to increase rapidly.

03. What does IQ include?

Although we now conduct a lot of analysis on the factors of IQ, including:

1. Brain capacity

2. Parietal lobe and frontal lobe width

3. Brain surface area. The more wrinkles on the brain surface, the more grooves and gyri there are, the more neurons there are. As the brain area increases, the cell capacity also increases. Relatively speaking, people with more brain cells have higher IQs.

4. Brain Connections

In fact, the first three basically represent one content, that is, the capacity issue. Of course, for cross-species or ancient creatures, brain capacity is the easiest to analyze (just measure the skull) (the brain capacity here should be understood as relative brain capacity). The last brain connection is more reflected in learning.

Of course, in more recent events, such as the development of tribes after entering primitive society and the advancement of human beings in the Paleolithic and Neolithic Ages, the role of intelligence has become more significant, especially in the manufacture of tools, the domestication of crops and domestic animals, which require higher intelligence. After all, technology is the primary productive force. As a result, the human population with higher and higher IQs has become larger and larger, and the continuous screening process has intensified the role of IQ. These have been analyzed a lot in other answers, so I won’t repeat them.

04. Additional words

Although today we have discovered that there are indeed some genes that are clearly related to human intelligence, including:

1. Sequence variant sites (rs31480, etc.) located in the 23.2-33.1 region of the long arm of chromosome 5 are strongly correlated with brain volume

2. ARHGAP11B helps basal brain stem cells reproduce, leading to the production of more neurons during human brain development and an increase in the volume of the brain responsible for advanced cognitive abilities such as speaking and thinking. This gene is only found in humans and our now extinct relatives, the Neanderthals and Denisovans.

3. HMGA2 gene and genes related to brain volume and intelligence

But the fact that these genes were selected shows that humans made an active choice in this process. That is, high intelligence plays a greater role in human survival. If we did not do this, then today we would be the various chimpanzees and apes shown on TV.

05. Finally, expectations for the future

I believe that even though there is a partial brain-body inversion phenomenon now, I think the screening of intelligence is still continuing, and in the future, human intelligence will show a spiral upward trend, but the overall trend will remain unchanged. Since brain capacity is the most basic factor of intelligence, humans may face a process of continuous skull enlargement in the future. During this process, if pregnant women have trouble giving birth, the proportion of caesarean sections may be further increased, and this increase in proportion will in turn allow for larger skulls to appear.

ps: Regarding brain capacity, although many studies have shown that there is no linear relationship between brain capacity and IQ, it does not mean that brain capacity is not important. On the contrary, brain capacity is the basis of the cerebral sulcus or prefrontal lobe. Without capacity, the latter is just empty talk.

There is an interesting metaphor. Fertilizers can promote crop yields, but if you think that fertilizers are the only factor, or even only use fertilizers on crops without using other things (light, water, carbon dioxide, etc.), then the crops will die directly.